The Cano-Limon Covenas pipeline, run by state-owned Ecopetrol, was bombed at a 485-kilometer section that runs near the border with Venezuela in Arauca province, Reuters reported. Pumping of crude into the pipeline has been halted, according to Ecopetrol.

The pipeline has a 210,000 barrel per day capacity, and transits crude produced by U.S.-based Occidental Petroleum to the port of Covenas in the Caribbean, which is the country’s main export facility. The Cano Limon oilfields, operated by Occidental, account for 30 percent of Colombia’s total oil output.

There are two major rebel groups operating in Colombia: FARC (the Revolutionary Armed Forces of Colombia), the largest, and ELN, the second-largest.

A similar attack on the same pipeline in April was also attributed to the ELN.

Suspicion is also resting on the ELN due to the status of peace talks between the government and the two rebel groups. While peace talks are proceeding with FARC, boosted to some extent by FARC’s public renouncing of kidnapping in 2012, the ELN has refused to follow suit, making peace talks more challenging.

Rebel groups have been responsible for a significant drop in production in Colombia. In March, according to Bloomberg data, production dropped to 916,000 barrels per day, down 8 percent from December 2015, while daily crude exports slid 14 percent from the previous month.